Jet pipe relay



Jan. 19, 1943.

Filed July 18, 1958 G. Z. VON MANTEUFFEL JET PIPE RELAY 2 Sheets-Sheet l /n ven for: GerZ'Zaegye 000M105 eZ J 1943- G. 2. VON MANTEUFFEL 2,308,662

JET PIPE RELAY Filed July 18, 1938 2 Sheets-Sheet 2 ?atentecl Jan. 19, 1943 JET rrrn RELAY Gert Zoege von Manteufl'el, Berlin-Dahlem, Ger= many; vested in the Alien Property Custodian Application July 1a, 1938, Serial No. 219,926 In Germany July 19, 1937 I 4 Claims.

The present invention relates to improvements in jet pipe relays for servo-motors for control devices. The relative position of the jet pipe and of the receiving passages is controlled in accordance with a controlling impulse in order to direct the pressure fluid jet relative to the receiving passages, thereby varying the pressure in the passages in accordance with said controlling impulse.

The object of the invention is to improve the well known jet pipe relays of this type in order to increase the emciency of the relay. By increase in efliciency is meant greater difierential .pressure for the same deflection of the jet pipe.

A greater difierential pressure for the same defiection as compared with the known types of jet pipes will cause the control device to move faster and thus become more sensitive for small deflections. Thus the main object of the invention is to so space the centers or the mid points of the receiving orifices of the two fluid receiving passages or nozzles so that such centers or mid points are less than that which provides a minimum positive pressure and greater than that which gives the maximum positive pressure when the jet pipe is in the central position relative to said orifices.

A further object of the invention is to so arrange and direct the receiving passages that all disturbing influences, caused by the return flow ofthe pressure fluid from the servo-motor exhausting from the respective passage, are avoided, by directing such exhausting fluid in such a way that it will not strike orinfluence the jet p pe.

Further aims, objects and advantages of the invention will appear from a consideration of the following description, together with the accompanying drawings showing, for purely illustrative purposes, one embodiment of the invention.

Referring to the drawings:

Fig. 1 is a diagrammatic view, partly in section, of a known jet pipe relay;

Fig. 2 is an end view of the receiving or distributor block with a portion of the jet pipe in section, according to the invention;

Fig. 3 is a top view of the receiving block showing the inlet orifices;

Fig. 4 is a sectional view taken on line A-B of Fig. 3; and

Fig. 5 is a diagram indicating the efliciency obtained by applicants invention.

The jet pipe I is provided with a pressure fluid at p and is directed into the passages 4 and 5 to control a servo-motor 3. The control of the jet pipe deflections is caused by any controlling impulse such as a diaphragm casing 2 which is acted upon by a controlling pressure. This structure of a jet pipe relay and its controls are well known in the art.

According to the present invention, the distance between the centers or the mid points of the two receiving orifices of the passages or nozzles 4 and 5 should be less than that which produces a minimum positive pressure and greater than that which produces a maximum positive pressure when the jet pipe is in the central position. The sensitivity of the relay can be chosen in this range and the maximum sensitivity is obtained if the distance of the centers of the oriflces is about greater than the diameter of the receiving orifices, as illustrated.

Hitherto, in order to have the apparatus highly sensitive, the distance between the centers of the receiving passages or nozzle or in other words the minimum width of the ridge separating the two inlet orifices of the passages from one another, has been made as small as possible consistent with obtaining a predetermined pressure difiference in the servo-motor with the smallest possible jet pipe deflection.

Now referring to Figs. 2 and 3 of the drawings, it will be seen that in carrying this invention into practice the distance 6 between the centers of the inlet orifices of the passages 4 and 5 at the ends adjacent the jet pipe i (Fig. 3) is made considerably greater than has been the practice hitherto, the distance between such centers being according to this invention about 50% greater than the nozzle diameter 1 of the jet pipe I.

The required differential pressure is obtained with a smaller jet pipe deflection because the differential pressure increases faster if the orifice centers are moved away from each other, while in the usual constructions, in which the ridge separating the two nozzles from one another is as small as possible, the jet produces a consid-' erable influence on the pressure conditions in the other orifice evenin'the deflected position of the jet pipe, in which it was exactly opposite the receiving orifice into which it was discharging. I

It is further to be noted that by increasing the distance between the centers of the orifices there also results a decrease of the pressure at the receiving orifices when the jet pipe is in the middle position. -The same applies to a deflected position of the jet pipe due to the fact that. the pressure in the discharging passage is smaller than that in the hitherto known jet pipe relaysso that a smaller pressure in the charging passage sufiices to obtain the same pressure difierence between charging and discharging passages, i. e., the pressure difference acting in the servo-motor. In the case of a pneumatically operating jet pipe relay, the compression pressure of the pressure medium is smaller and hence the volume of the pressure medium greater, resulting in a greater stroke velocity of the servo-motor at the same jet velocity.

It has proved practical to arrange for the middle pressure, that is to say the pressure existing in the nozzles in the middle position of the jet pipe to be about 50% of the supply pressure, because from this results a symmetrical characteristic and a greater steepness of the pressure curve on each side of the middle position (Fig. 5).

If for any reason it is desired to achieve a maximum adjusting or piston speed with reference to an existing energy supply, then according to the basic idea of the invention, the pressure in the passages in the middle position of the jet pipe can further be reduced by a further enlargement of the distance between the centers of the orifices.

The increase in the distance 6 between the centers of the passages permits an increase in the size of the inlet orifices of the receiving passages 4 and 5 (e. g., in the case of hydraulic operation), without losing the advantages mentioned above.

The passages 4 and 5 are arranged crosswise with respect to one another as will be seen from Fig.- 3 of the drawings. Thus, if the axes III and II of the two passages are projected on a common plane parallel to the plane in which the axis of the jet pipe I moves when the jet pipe is deflected the projection of the two axes I and II converge towards one another in a direction from the receiving ends of the passages towards the opposite ends thereof, and these projected axes intersect in this common plane at a point I3 disposed behind the plane I2 containing the orifices of the passages 4 and 5. Moreover, the crosswise arrangement of the passages 4 and 5 is such that the minimum distance 6' (Fig. 3) between the axes I0 and II of the passages is also disposed behind the plane I2, that is on the side of the plane I2 remote from the jet pipe I. It will also be seen that if both of the axes III and II were projected on the plane AB (i. e., the plane of the section shown in Fig. 4), these axes would in that figure diverge in a direction away from the plane I2. The passages 4 and 5 preferably have a frusto-conical internal configuration with the narrowest ends disposed in the plane I2.

The generatrix lines 8 and 9 in Fig. 3 of the two passages 4 and 5, must be at a sufficient distance apart in order to avoid one passage penetrating the other, and the said distance must be greater than a certain minimum measurement in view of technical reasons of manufacture.

Increasing the distance 6 permits (Fig. 3), the projections of the two axes I0 and I I of the passages 4 and 5 into the plane of deflection of the jet pipe I to be arranged so as to make a larger angle a. with the perpendicular to the plane I2 passing through the point of intersection I3 of the projected axes Ill and II than was hither-to usual in practice.

It will be appreciated the present arrangement is distinguished from the known arrangement shown in Fig. 1, in that the intersection of the from the servo-motor.

projected axes I0 and I I lies in front of the plane I2 in the latter construction while in the arrangement according to this invention the intersection of the axes I0 and II is behind or below the plane I2.

As will be readily understood from Fig. 2, the greater the angle a, the less danger there will be of the jet pipe being struck by the discharge flow The less this danger, the nearer the jet pipe nozzles may be brought to the plane I2 comprising the inlet orifices. However, the greater the angle a, the greater will be the deflection of the jet upon entering the inlet orifice. Such a deflection of course results in an undesirable loss of pressure. If the Jet is perpendicularto the plane of the inlet orifice of the receiving nozzle, a predetermined pressure will be produced in the nozzle. Now if the angle between the jet and the plane of the inlet orifice decreases up to approximately zero, obviously the pressure produced in the receiving nozzles likewise decreases up to approximately zero. Accordingly any decrease of said angle between the jet and the plane of the inlet orifice must result in a reduction of pressure or in other words, in loss of pressure. Therefore, this deflection is to be taken into consideration in determining the angle a or the distance I4 of the intersection point I3 from the plane I2. The best results are obtained if the distance I4 is about 5 times the distance Ii between the centers of the inlet orifices of the nozzles 4 and 5.

The jet deflection or change of direction of the jet leaving the jet pipe and entering the receiving passages can best be seen from Fig. 4. It will be seen that the jet issuing from the jet pipe I is directed approximately normally to the plane I2, while the axis II] of the receiving passage 4 (which is the passage shown in the figure), is inclined to the normal. In the illustrated embodiment of the invention the angle of inclination to the normal is 18 whereas hitherto it has been about 25. Further decrease of the said angle of inclination results in only slight gain of efficiency, and an angle of 18 is found to give the most beneficial results in the desired efiiciency of the apparatus.

It should be pointed out that Fig. 1 is not drawn to scale and is merely diagrammatic, but Figs. 2 to 4 are represented strictly to scale.

The operation of the present invention is made clear by the diagram illustrated in Fig. 5. In this diagram the pressures set up in the receiving passages 4, 5 are plotted as ordinates and as a function of the displacement of the jet pipe (abscissa), the two dotted curves a, b being obtained in the case of the known jet pipe relay with a small distance between the centers, whereas the corresponding pressures in the case of the arrangement according to the invention are shown by the curves a, b. Comparison of the curves at and b with the curves a, b shows that the pressure in the middle position of the jet pipe is considerably less than has hitherto been the case. Now from the two curves a and b the pressure difierence between the two receiving passages 4 and 5 can be derived as a function of the displacement of the jet pipe, in that, starting from the zero position of the jet pipe, the perpendicular distance between the two right hand limbs of the curves a and b is measured off at successive places and these distances are plotted as ordinates against the abscissa. Thus for example a: is measured and is marked off from the abscissa ordinate so as to terminate at the point X. As a result of plotting the pressure differences at a series of points along a and b, the pressure difference curve is obtained. In the same way a pressure difference curve c is obtained for the curves a and b. Thus for example 1 is measured and marked oil from the abscissa ordinate so as to terminate at the point Y. The curve c is steeper than the curve 0, that is to say, for one and the same displacement of the jet pipe the pressure diflerence in the construction according to the invention is greater than in the known construction, or in other words, for one and the same pressure difference the construction, according to the invention, requires a smaller displacement of the jet pipe than in the case of the known relay.

It is to be noted that the present invention is not restricted to the particular embodiment herein shown and described. Many changes may be made by those skilled in the art without departing from the general spirit of my invention as defined in the following claims.

I claim as my invention:

1. A jet-pipe relay comprising a jet-pipe supplied with a pressure fluid and two receiving passages each having an inlet orifice in operative relation with the jet pipe, the diameter of the inlet orifices being made greater than the diam- -'eter of the outlet orifice of the jet pipe. said passages having the centres of their inlet orifices spaced apart by a distance approximately 50% greater than the diameter of the outlet opening of the jet-pipe, said passages being arranged with their axes in such a manner that, if the axes are projected on to the plane of movement of the longitudinal axis of the jet-pipe, the projected axes intersect at a position which is farther from said jet-pipe than the inlet orifices of said receiving passages are from the jet-pipe, while if the axes are projected on to a plane transverse to and intersecting the last mentioned plane and also substantially parallel to the axes of both passages, the projected axes first converge, intersect and then diverge regarding these axes in a direction from the inlet orifice ends of the passages towards the other ends of the latter.

2. A jet-pipe relay according to claim 1, in which the distance between the plane containing the inlet orifices of said passages and the point of intersection of said projected axes is approximately five times the distance between the centers of the inlet orifices of said passages.

3. A jet-pipe relay according to claim 1, in which the outside surface of the mouth part of the jet-pipe is conical terminating with a relatively sharp edge at its discharge end.

4. A jet-pipe relay comprising a jet-pipe sup plied with a pressure fluid and two receiving nozzles each with an inlet orifice at one end, said nozzles having their axes, if projected on to the plane of movement of the longitudinal axis of the jet pipe, intersecting at a position which is farther from said jet-pipe than the inlet orifices of said receiving nozzles are from the jetpipe, and the axes, if projected on to a plane transverse to and intersecting the last mentioned plane and also substantially parallel to the axes of both nozzles, will first converge, intersect and then diverge relative to these axes in a direction from the inlet orifice ends of the nozzles towards the other ends of the latter, the distance between the plane of the inlet orifices of said nozzles and the point of intersection of the axes of said nozzles projecting into said plane of movement of the longitudinal axis of the jet-pipe being approximately five times the distance between the centres of the inlet orifices of said nozzles.

GERT zones von mum. 

